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Abstract Quantum Chromodynamics predicts a phase transition from hadronic matter to quark–gluon plasma (QGP) at high temperatures and energy densities, where quarks and gluons (partons) are no longer confined within hadrons. The QGP forms in ultrarelativistic heavy-ion collisions. Anisotropic flow coefficients, quantifying the azimuthal expansion of produced matter, probe QGP properties. Flow measurements in high-energy heavy-ion collisions show a distinctive grouping of anisotropic flow for baryons and mesons at intermediate transverse momentum – a feature associated with flow imparted at the quark level, confirming QGP existence. The observation of QGP-like features in proton–proton and proton–ion collisions has sparked debate about QGP formation in smaller systems. For the first time, we demonstrate the distinctive grouping of anisotropic flow for baryons and mesons in high-multiplicity proton–lead and proton–proton collisions at the Large Hadron Collider (LHC). These results are described by a model including hydrodynamic flow followed by hadron formation via quark coalescence, consistent with the formation of partonic flowing systems in these collisions. 

A<sc>bstract</sc> The measurement of three-dimensional femtoscopic correlations between identical charged kaons (K^±K^±) produced in p–Pb collisions at center-of-mass energy per nucleon pair$$\sqrt{{s}_{\text{NN}}}=5.02$$TeV with ALICE at the LHC is presented for the first time. This measurement, supplementary to those in pp and Pb–Pb collisions, allows understanding the particle-production mechanisms at different charged-particle multiplicities and provides information on the dynamics of the source of particles created in p–Pb collisions, for which a general consensus does not yet exist. It is shown that the measured source sizes increase with charged-particle multiplicity and decrease with increasing pair transverse momentum. These trends for K^±K^±are similar to the ones observed earlier in identical charged-pion and$${\text{K}}_{\text{s}}^{0}{\text{K}}_{\text{s}}^{0}$$correlations in Pb–Pb collisions at various energies and inπ^±π^±correlations in p–Pb collisions at$$\sqrt{{s}_{\text{NN}}}=5.02$$TeV. At comparable multiplicity, the source sizes measured in p–Pb collisions agree within uncertainties with those observed in pp collisions, and there is an indication that they are smaller than those observed in Pb–Pb collisions. The obtained results are also compared with predictions from the hadronic interaction model EPOS 3, which tends to underestimate the source size for the most central collisions and agrees with the data for semicentral and peripheral events. Furthermore, the time of maximal emission for kaons is extracted. It turns out to be comparable with the value obtained in highly peripheral Pb–Pb collisions at the same energy, indicating that the kaon emission evolution is similar to that in p–Pb collisions. 

This paper presents the first measurement of the angle between different jet axes (denoted as $\mathrm{\Delta }{R}_{\mathrm{axis}}$) in $\text{Pb-Pb}$collisions. The measurement is carried out in the 0–10 % most-central events at $\sqrt{s_{NN}}=5.02$TeV. Jets are assembled by clustering charged particles at midrapidity using the $\text{anti-}{k}_{\mathrm{T}}$algorithm with resolution parameters $R=0.2$and 0.4 and transverse momenta in the intervals $40<p_{\mathrm{T}}^{\mathrm{ch}\mathrm{jet}}<140\mathrm{GeV}/c$and $80<p_{\mathrm{T}}^{\mathrm{ch}\mathrm{jet}}<140\mathrm{GeV}/c$, respectively. Measurements at these low transverse momenta enhance the sensitivity to quark-gluon plasma (QGP) effects. A comparison to models implementing various mechanisms of jet energy loss in the QGP suggests that the observed narrowing of the $\text{Pb-Pb}$distribution relative to $\mathit{pp}$can be explained if quark-initiated jets are more likely to emerge from the medium than gluon-initiated jets. These new measurements disfavor intrajet $p_{\mathrm{T}}$broadening as implemented in a simple model calculation with the Baier-Dokshitzer-Mueller-Peigne-Schiff formalism for energy loss in the QGP. The comparison of $\text{Pb-Pb}$and $\mathit{pp}$collisions shows sensitivity to the angular scale at which the QGP can resolve two independent splittings, favoring mechanisms that incorporate incoherent energy loss. 

Abstract The transverse momentum spectra and integrated yields of anti-$$\Sigma $$ $\Sigma$hyperons ($$\overline{\Sigma }^{\pm } $$ ${\overline{\Sigma }}^{\pm }$) have been measured in$$\text {pp}$$ $\text{pp}$and$$\text {p}{-}\text {Pb}$$ $\text{p}-\text{Pb}$collisions at$$\sqrt{s_{\textrm{NN}}}=5.02$$ $\sqrt{s_{\text{NN}}}=5.02$TeV with the ALICE experiment. Measurements are performed via the newly accessed decay channel$$\overline{\Sigma }^{\pm } \!\!\rightarrow \mathrm{\overline{n}} \pi ^{\pm }$$ ${\overline{\Sigma }}^{\pm }\to \overline{n}{\pi }^{\pm }$. A new method of antineutron reconstruction with the PHOS electromagnetic spectrometer is developed and applied to this analysis. The$$p_{\textrm{T}}$$ $p_{\text{T}}$spectra of$$\overline{\Sigma }^{\pm } $$ ${\overline{\Sigma }}^{\pm }$are measured in the range$$0.5<3$$ $0.5<p_{\text{T}}<3$GeV/$$c$$ $c$and compared to predictions of the PYTHIA 8, DPMJET, PHOJET, EPOS LHC and EPOS4 models. The EPOS LHC and EPOS4 models provide the best descriptions of the measured spectra both in$$\text {pp}$$ $\text{pp}$and$$\text {p}{-}\text {Pb}$$ $\text{p}-\text{Pb}$collisions, while models which do not account for multiparton interactions provide a considerably worse description at high$$p_{\textrm{T}}$$ $p_{\text{T}}$. The total yields of$$\overline{\Sigma }^{\pm } $$ ${\overline{\Sigma }}^{\pm }$in both$$\text {pp}$$ $\text{pp}$and$$\text {p}{-}\text {Pb}$$ $\text{p}-\text{Pb}$collisions are compared to predictions of the Thermal-FIST model and dynamical models PYTHIA 8, DPMJET, PHOJET, EPOS LHC and EPOS4. All models reproduce the total yields in both colliding systems within uncertainties. The nuclear modification factors$$R_\textrm{pPb}$$ $R_{\text{pPb}}$for both$$\overline{\Sigma }^{+} $$ ${\overline{\Sigma }}^{+}$and$$\overline{\Sigma }^{-} $$ ${\overline{\Sigma }}^{-}$are evaluated and compared to those of protons,$$\Lambda $$ $\Lambda$and$$\Xi $$ $\Xi$hyperons, and predictions of EPOS LHC and EPOS4 models. No deviations of$$R_\textrm{pPb}$$ $R_{\text{pPb}}$for$$\overline{\Sigma }^{\pm } $$ ${\overline{\Sigma }}^{\pm }$from the model predictions or measurements for other hadrons are found within uncertainties. 

Abstract The measurement of$$\Sigma ^{+}$$ ${\Sigma }^{+}$production in pp collisions at$$\sqrt{s}=13$$ $\sqrt{s}=13$ TeV is presented. The measurement is performed at midrapidity in both minimum-bias and high-multiplicity pp collisions at$$\sqrt{s} =13$$ $\sqrt{s}=13$ TeV. The$$\Sigma ^{+}$$ ${\Sigma }^{+}$is reconstructed via its weak-decay topology in the decay channel$$\Sigma ^{+} \rightarrow \mathrm{{p}} + \pi ^{0}$$ ${\Sigma }^{+}\to p+{\pi }^0$with$$\pi ^{0} \rightarrow \gamma + \gamma .$$ ${\pi }^0\to \gamma +\gamma .$In a novel approach, the neutral pion is reconstructed by combining photons that convert in the detector material with photons measured in the calorimeters. The transverse-momentum$$(p_{\textrm{T}})$$ $\left(p_{\text{T}}\right)$distributions of the$$\Sigma ^{+}$$ ${\Sigma }^{+}$and its rapidity densities$${\textrm{d}}N$$ $\text{d}N$/$${\textrm{d}}y$$ $\text{d}y$in both event classes are reported. The$$p_{\textrm{T}}$$ $p_{\text{T}}$spectrum in minimum-bias collisions is compared to QCD-inspired event generators. The ratio of$$\Sigma ^{+}$$ ${\Sigma }^{+}$to previously measured$$\Lambda $$ $\Lambda$baryons is in good agreement with calculations from the Statistical Hadronization Model. The high efficiency and purity of the novel reconstruction method for$$\Sigma ^{+}$$ ${\Sigma }^{+}$presented here will enable future studies of the interaction of$$\Sigma ^{+}$$ ${\Sigma }^{+}$with protons in the context of femtoscopic measurements, which could be crucial for understanding the equation of state of neutron stars. 

Abstract The dependence of$$\textrm{f}_{0}$$ ${\text{f}}_0$(980) production on the final-state charged-particle multiplicity is reported for proton–proton (pp) collisions at the centre-of-mass energy,$$\sqrt{s}=$$ $\sqrt{s}=$ 13 TeV. The production of$$\textrm{f}_{0}$$ ${\text{f}}_0$(980) is measured with the ALICE detector via the$$\textrm{f}_0 (980) \rightarrow \pi ^{+}\pi ^{-}$$ ${\text{f}}_0\left(980\right)\to {\pi }^{+}{\pi }^{-}$decay channel in a midrapidity region of$$|y|<$$ $\left|y\right|<$ 0.5. The evolution of the integrated yields and mean transverse momentum of f$$_{0}$$ $_0^{}$(980) as a function of charged-particle multiplicity measured in pp at$$\sqrt{s}=$$ $\sqrt{s}=$ 13 TeV follows the trends observed in pp at$$\sqrt{s}=$$ $\sqrt{s}=$ 5.02 TeV and in proton–lead (p–Pb) collisions at$$\sqrt{s_{\textrm{NN}}}=$$ $\sqrt{s_{\text{NN}}}=$ 5.02 TeV. Particle yield ratios of$$\textrm{f}_{0}$$ ${\text{f}}_0$(980) to$$\pi ^{\pm }$$ ${\pi }^{\pm }$and$$\textrm{K}^{*}$$ $\text{K}_{}^{\ast }$(892)$$^{0}$$ $_{}^0$are found to decrease with increasing charged-particle multiplicity. These particle ratios are compared with calculations from the canonical statistical thermal model as a function of charged-particle multiplicity. The thermal model calculations provide a better description of the decreasing trend of particle ratios when no strange or antistrange quark composition for f$$_{0}$$ $_0^{}$(980) is assumed, which suggests that the data do not support significant hidden strangeness in the$$\textrm{f}_{0} (980)$$ ${\text{f}}_0\left(980\right)$. 

This Letter presents measurements of long-range transverse-momentum correlations using a new observable, $v_0\left(p_{\mathrm{T}}\right)$, serving as a probe of event-by-event radial-flow fluctuations, the underlying radial expansion, and the medium’s properties in heavy-ion collisions. Results are reported for inclusive charged particles, pions, kaons, and protons across various centrality intervals in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$, recorded by the ALICE detector. A pseudorapidity-gap technique, similar to that used in anisotropic-flow studies, is employed to suppress short-range correlations. At low $p_{\mathrm{T}}$, a characteristic mass ordering consistent with hydrodynamic collective flow is observed. At higher $p_{\mathrm{T}}$( $>3\mathrm{GeV}/c$), protons exhibit larger $v_0\left(p_{\mathrm{T}}\right)$than pions and kaons, in agreement with expectations from quark-recombination models. Comparisons to viscous hydrodynamic calculations with varying bulk viscosity and equation of state demonstrate the sensitivity of the $v_0\left(p_{\mathrm{T}}\right)$observable to these key medium properties. The findings establish $v_0\left(p_{\mathrm{T}}\right)$as a valuable addition to the set of observables used in Bayesian analyses for extracting the transport properties and constraining the equation of state of strongly interacting matter, while also helping to systematically explore its sensitivity and impact within such global studies. 

Abstract High-energy hadronic collisions generate environments characterized by temperatures above 100 MeV (refs. ^1,2), about 100,000 times hotter than the centre of the Sun. At present, it is therefore unclear how light (anti)nuclei with mass numberAof a few units, such as the deuteron,³He or⁴He, each bound by only a few MeV, can emerge from these collisions^3,4. Here, the ALICE Collaboration reports that deuteron–pion momentum correlations in proton–proton (pp) collisions provide model-independent evidence that about 90% of the observed (anti)deuterons are produced in nuclear reactions⁵following the decay of short-lived resonances, such as the Δ(1232). These findings, obtained by the ALICE Collaboration at the Large Hadron Collider, resolve a gap in our understanding of nucleosynthesis in ultrarelativistic hadronic collisions. Apart from offering insights on how (anti)nuclei are formed in hadronic collisions, the results can be used in the modelling of the production of light and heavy nuclei in cosmic rays⁶and dark-matter decays^7,8. 

A<sc>bstract</sc> The first measurement at midrapidity (|y|<0.5) of the production yield of the strange-charm baryons$${\Xi }_{\text{c}}^{+}$$and$${\Xi }_{\text{c}}^{0}$$as a function of transverse momentum (p_T) in different charged-particle multiplicity classes in proton-proton collisions at$$\sqrt{s}=13$$TeV with the ALICE experiment at the LHC is reported. The$${\Xi }_{\text{c}}^{+}$$baryon is reconstructed via the$${\Xi }_{\text{c}}^{+}\to {\Xi }^{-}{\pi }^{+}{\pi }^{+}$$decay channel in the range 4< p_T<12 GeV/c, while the$${\Xi }_{\text{c}}^{0}$$baryon is reconstructed via both the$${\Xi}_{\text{c}}^{0}\to {\Xi}^{-}{\pi }^{+}$$and$${\Xi}_{\text{c}}^{0}\to {\Xi}^{-}{\text{e}}^{+}{\nu }_{\text{e}}$$decay channels in the range 2< p_T<12 GeV/c. The baryon-to-meson$$\left({\Xi}_{\text{c}}^{0,+}/{\text{D}}^{0}\right)$$and the baryon-to-baryon$$\left({\Xi}_{\text{c}}^{0,+}/{\Lambda}_{\text{c}}^{+}\right)$$production yield ratios show no significant dependence on multiplicity. In addition, the observed yield ratios are not described by theoretical predictions that model charm-quark fragmentation based on measurements at e⁺e⁻and e⁻p colliders, indicating differences in the charm-baryon production mechanism in pp collisions. A comparison with different event generators and tunings, including different modelling of the hadronisation process, is also discussed. Moreover, the branching-fraction ratio of$${\text{BR}}\left({\Xi}_{\text{c}}^{0}\to {\Xi }^{-}{\text{e}}^{+}{\nu }_{\text{e}}\right)/{\text{BR}}\left({\Xi}_{\text{c}}^{0}\to {\Xi }^{-}{\pi }^{+}\right)$$is measured as 0.825 ± 0.094 (stat.) ± 0.081 (syst.). This value supersedes the previous ALICE measurement, improving the statistical precision by a factor of 1.6. 

Abstract This paper presents the measurement of the isolated prompt photon inclusive production cross section in pp and p–Pb collisions by the ALICE Collaboration at the LHC. The measurement is performed in p–Pb collisions at centre-of-mass energies per nucleon pair of$$\sqrt{s_{\text {NN}}}={5.02}\,\textrm{TeV}$$ $\sqrt{s_{\text{NN}}}=5.02\text{TeV}$and 8.16 TeV, as well as in pp collisions at$$\sqrt{s}={5.02}\,\textrm{TeV}$$ $\sqrt{s}=5.02\text{TeV}$and 8 TeV. The cross section is obtained at midrapidity$$(|y|<0.7)$$ $\left(\right|y|<0.7)$using a charged-track based isolation momentum$$p_\textrm{T}^{\text {iso,~ch}}<{1.5}\,\textrm{GeV}/c$$ $p_{\text{T}}^{\text{iso, ch}}<1.5\text{GeV}/c$in a cone with radius$$R=0.4$$ $R=0.4$. The data for both collision systems are well reproduced by perturbative QCD (pQCD) calculations at next-to-leading order (NLO) using recent parton distribution functions for free (PDF) and bound (nPDF) nucleons. Furthermore, the nuclear modification factor$$R_{\text {pA}}$$ $R_{\text{pA}}$for both collision energies is consistent with unity for$$p_{\textrm{T}}$$ $p_{\text{T}}$$$>{20}\,\textrm{GeV}/c$$ $>20\text{GeV}/c$. However, deviations from unity ($$R_\textrm{pA}<1$$ $R_{\text{pA}}<1$) of up to 20% are observed for$$p_{\textrm{T}}$$ $p_{\text{T}}$$$<{20}\,\textrm{GeV}/c$$ $<20\text{GeV}/c$with limited significance, indicating the possible presence of nuclear effects in the initial state of the collision. The suppression increases with decreasing$$p_{\textrm{T}}$$ $p_{\text{T}}$with a significance of$$2.3\upsigma $$ $2.3\sigma$for a non-zero slope and yields$$R_{\textrm{pA}}<1$$ $R_{\text{pA}}<1$with a significance of$$1.8\upsigma $$ $1.8\sigma$at$$\sqrt{s_{\textrm{NN}}}={8.16}\,\textrm{TeV}$$ $\sqrt{s_{\text{NN}}}=8.16\text{TeV}$for$$p_{\textrm{T}}$$ $p_{\text{T}}$$$<{20}\,\textrm{GeV}/c$$ $<20\text{GeV}/c$. In addition, a significance of$$1.1\upsigma $$ $1.1\sigma$is observed for$$R_{\textrm{pA}}<1$$ $R_{\text{pA}}<1$at the lower collision energy$$\sqrt{s_{\textrm{NN}}}={5.02}\,\textrm{TeV}$$ $\sqrt{s_{\text{NN}}}=5.02\text{TeV}$for$$p_{\textrm{T}} < {14}\,\textrm{GeV}/c$$ $p_{\text{T}}<14\text{GeV}/c$. The magnitude and shape of the suppression are consistent with pQCD predictions at NLO using nPDFs that incorporate nuclear shadowing effects in the Pb nucleus.